(a) Field
The invention relates to a photomask and a method of forming a pattern using the same.
(b) Description of the Related Art
Various processes of manufacturing a semiconductor device or a display device include a process of stacking an etching target material, such as metal, on a substrate, applying a photoresist film, and then performing exposure and development for forming various patterns of the semiconductor device or the display device. Among them, the exposure processing forms a desired pattern from the photoresist film by irradiating light, such as ultraviolet rays, to the photoresist film which is on the stacked etching target material such as by using a light exposer and a photomask for exposure.
Resolution of the light exposer is limited to approximately half of a wavelength of the light used for exposure due to a diffraction limit, so that accuracy and a degree of fineness of a desired pattern are limited.
There is increasing need to form a fine pattern according to the development of display devices, such as liquid crystal display devices, organic light emitting diode display devices, electrophoretic display devices, microelectromechanical (“MEMS”) display devices, and three-dimensional (“3D”) display devices, as well as relating to several semiconductor devices. Particularly, a fine pattern of a display device in a business field of a flat panel display is desired in order to improve a display quality where a size of a pixel is decreased in order to improve resolution of the flat panel display. However, forming the fine pattern may exceed a limit of resolution of a light exposer used in forming the fine pattern.
According to the desire of improving the display quality and resolution of a display device, a light exposer having high resolution may be used in forming the fine pattern. For example, resolution may be increased by changing a light source used in the light exposer or by increasing a value of the numerical aperture (“NA”) of the light exposer. However, to affect the increase in resolution, the light exposer may be remodeled and/or new equipment may be introduced, which undesirably increases a cost and time.